Something that I haven't seen mentioned: deferred pay is a huge problem in startups. Essentially, the founders are asking you to take venture risk with your salary, but they're not compensating you for that risk (I'm assuming they're not paying you 30% interest on that deferred amount.) Letting them defer your pay actually encourages them to wait as long as possible before raising a new round of funding, because the…
The investors may balk at applying their funds to deferred compensation, asking the founders to re-spin the employment agreement to convert the deferred compensation to common (or options) prior to the investment, further diluting and deferring it.
Why would the founders do that? They would be faced with a choice of no funding or new funding applied to salaries going forward.